/**

* Difficulty:

* Medium

*

* Desc:

* Given an absolute path for a file (Unix-style), simplify it.

*

* Example:

* path = "/home/", => "/home"

* path = "/a/./b/../../c/", => "/c"

*

* Note:

* 1. Did you consider the case where path = "/../"?

* In this case, you should return "/".

* 2. Another corner case is the path might contain multiple slashes '/' together, such as "/home//foo/".

* In this case, you should ignore redundant slashes and return "/home/foo".

*

* 简化类似 Unix 下的路径。注意处理类似 '/../' 或者 '/home//ecmadao' 的情况

*/

/**

* 思路：

* 构建一个树的结构，每个节点保留其当前目录名称和父节点

* 遍历输入的路径，获取到最后的结果节点，然后向上遍历，最后得到合法的最简洁的路径

*/

var Node = function(folder, father) {

this.folder = folder;

this.father = father;

};

/**

* @param {string} path

* @return {string}

*/

var simplifyPath = function(path) {

var node = new Node('', null);

var paths = path.split('/');

for (var i = 0; i < paths.length; i += 1) {

var p = paths[i];

if (!p || p === '.') continue;

if (p === '..') {

if (!node.father) continue;

node = node.father;

} else {

node = new Node(p, node);

}

}

var result = '';

while(node.father) {

result = result ? node.folder + '/' + result : node.folder;

node = node.father;

}

return '/' + result;

};